Britney Spears Does Top 10 List on Letterman

And the No. 1 reason to read this story ... Britney Spears in a bikini!

The pop star stripped down to a little black bathing suit and tucked a red hibiscus in her hair to deliver the Top 10 list Tuesday night in her return to The Late Show with David Letterman.

In her first appearance since a cameo three years ago, Spears struck one sexy pose after another, crossing and uncrossing her legs, in the pre-taped segment in which she counted down the way things would be different if she were president.

"Three words: Vice President Diddy," she proclaimed, according to audience members. Also on the list: "Free pies for everybody!" and "Costume changes during press conferences."

And the top item on the list: "The media would pay attention to me."

Spears, 27, recently finished the European leg of her Circus tour and begins another string of concerts in America on Aug. 20.